Method for operating an active thermal energy storage system

Abstract

An active thermal energy storage system is disclosed which uses an energy storage material that is stable at atmospheric pressure and temperature and has a melting point higher than 32 degrees F. This energy storage material is held within a storage tank and used as an energy storage source, from which a heat transfer system (e.g., a heat pump) can draw to provide heating of residential or commercial buildings and associated hot water. The energy storage material may also accept waste heat from a conventional air conditioning loop, and may store such heat until needed. The system may be supplemented by a solar panel system that can be used to collect energy during daylight hours, storing the collected energy in the energy storage material. The stored energy may then be used during the evening hours to heat recirculation air for a building in which the system is installed.

1. A method for operating an energy storage system, comprising:
 providing a first volume of heat transfer fluid; 
 providing a second volume of thermal energy storage material (TESM), the TESM comprising a substantially solid material having a melting point above 32 degrees Fahrenheit (F), and a latent heat of fusion approaching that of water; and 
 providing a heating coil in contact with the second volume; 
 circulating the heat transfer fluid through the heating coil in the second tank; 
 wherein the step of circulating the heat transfer fluid transfers heat from the heat transfer fluid to the TESM when the temperature of the TESM is less than the temperature of the heat transfer fluid; and 
 wherein the step of circulating the heat transfer fluid transfers heat from the TESM to the heat transfer fluid when the temperature of the TESM exceeds the temperature of the heat transfer fluid. 
 
     
     
       2. The method of  claim 1 , further comprising the step of heating the heat transfer fluid using a heater. 
     
     
       3. The method of  claim 1 , further comprising:
 providing a solar panel having a fluid-filled recirculation loop in fluid communication with the heating coil of the second tank; and 
 moving the heating fluid through the recirculation loop and through the heating coil to transfer heat from the heating fluid to the TESM. 
 
     
     
       4. The method of  claim 1 , further comprising:
 providing an air conditioning loop for moving an air conditioning fluid between a first air conditioning coil disposed in said second tank and a second air conditioning coil disposed in a ventilation supply opening; and 
 moving the air conditioning fluid within the air conditioning loop to transfer energy between the TESM and air directed over an outer surface of said second air conditioning coil. 
 
     
     
       5. The method of  claim 4 , further comprising controlling a flow rate of said air conditioning fluid through said air conditioning loop using at least one of a compressor and a control valve. 
     
     
       6. The method of  claim 5 , further comprising operating the compressor in a first operating mode to move the air conditioning fluid through the air conditioning loop in a first direction, and operating the compressor in a second operating mode to move the air conditioning fluid through the air conditioning loop in a second direction opposite to said first direction. 
     
     
       7. The method of  claim 1 , wherein the TESM comprises a material selected from the group consisting of clathrate, imidazole, imidazolium chloride and a derivative of pyrrole. 
     
     
       8. A method for operating an energy storage system, comprising:
 providing a first tank for holding a quantity of fluid; 
 providing a second tank having a quantity of thermal energy storage material (TESM) disposed therein, the TESM comprising a substantially solid clathrate having a melting point above 32 degrees Fahrenheit (F); and 
 providing a fluid connection loop between the first and second tanks, the fluid connection loop being in fluid communication with the first tank and comprising a heating coil disposed within the second tank; 
 moving the fluid within the fluid connection loop to transfer heat from the fluid in the first tank to the TESM in the second tank when the fluid in the first tank has a temperature greater than a temperature of the TESM; and 
 moving the fluid within the fluid connection loop to transfer heat from the TESM in the second tank to the fluid in the first tank when the TESM has a temperature greater than the temperature of the fluid in the first tank. 
 
     
     
       9. The method of  claim 8 , further comprising heating the fluid in the first tank using a heater. 
     
     
       10. The method of  claim 8 , further comprising:
 providing a solar panel having a fluid-filled recirculation loop engaged with the fluid connection loop; and 
 moving the fluid within the recirculation loop and the fluid connection loop to transfer heat from the solar panel to the TESM. 
 
     
     
       11. The method of  claim 8 , further comprising:
 providing an air conditioning loop comprising a first air conditioning coil disposed within said second tank and a second air conditioning coil disposed within a building ventilation supply opening; and 
 moving an air conditioning fluid within said air conditioning loop to transfer energy between the TESM and air directed over an outer surface of the second air conditioning coil. 
 
     
     
       12. The method of  claim 11 , further comprising operating at least one of a compressor and a control valve to control a flow rate of said air conditioning fluid through said air conditioning loop. 
     
     
       13. The method of  claim 12 , further comprising operating the compressor in a first operating mode to move said air conditioning fluid through said air conditioning loop in a first direction, and operating the compressor in a second operating mode to move the air conditioning fluid through said air conditioning loop in a second direction opposite to said first direction. 
     
     
       14. The method of  claim 8 , wherein the TESM comprises a material selected from the group consisting of clathrate, imidazole, imidazolium chloride and a derivative of pyrrole. 
     
     
       15. A method for operating a thermal energy storage system, comprising:
 providing a first tank, a second tank, and an air distribution system; the first tank having a quantity of water disposed therein; and the second tank having a quantity of Thermal Energy Storage Material (TESM) disposed therein, the TESM comprising a phase change material having a melting point above 32 degrees Fahrenheit (F), and a latent heat of fusion approaching that of water; 
 moving water between the first and second tanks via a recirculation loop, the recirculation loop comprising at least a first coil disposed in the second tank; 
 moving a first heat transfer fluid between the second tank and the air distribution system via an air conditioning loop comprising a first air conditioning coil disposed in the second tank and a second air conditioning coil disposed in the air conditioning system to transfer energy between the TESM and air passed over the second air conditioning coil. 
 
     
     
       16. The method of  claim 15 , further comprising:
 providing a heat pump loop comprising a second heat transfer coil disposed within the first tank, and a third heat transfer coil disposed within the second tank; and 
 moving a second heat transfer fluid within the heat pump loop to transfer energy between the TESM in the second tank and the water in the first tank. 
 
     
     
       17. The method of  claim 16 , further comprising:
 operating at least one of a first compressor and first control valve to control movement of the heat transfer fluid through said air conditioning loop, and operating at least one of a second compressor and a second control valve to control movement of the second heat transfer fluid through the heat pump loop. 
 
     
     
       18. The method of  claim 17 , wherein the first compressor is a reversible compressor. 
     
     
       19. The method of  claim 15 , further comprising:
 providing a solar panel having a solar panel fluid loop in fluid communication with the recirculation loop between the first and second tanks; and 
 moving fluid within the solar panel fluid loop and through the recirculation loop to transfer energy from the solar panel to the TESM. 
 
     
     
       20. The method of  claim 15 , further comprising:
 providing a solar panel for generating a current for electrical power, and 
 heating the first tank using a heater powered by said electrical power. 
 
     
     
       21. The method of  claim 15 , wherein the TESM comprises a material selected from the group consisting of clathrate, imidazole, imidazolium chloride and a derivative of pyrrole. 
     
     
       22. The method of  claim 15 , wherein the TESM comprises clathrate. 
     
     
       23. A method of operating a thermal energy storage system, comprising:
 providing a first volume of heat transfer fluid; 
 providing a second volume of Thermal Energy Storage Material (TESM), the TESM comprising a phase change material having a melting point above 32 degrees Fahrenheit (F), and a latent heat of fusion approaching that of water; 
 providing a radiator circulation system; 
 moving the heat transfer fluid through a first coil in contact with the TESM to transfer energy between the heat transfer fluid and the TESM; and 
 moving a second heat transfer fluid from a second coil in contact with the second volume to a third coil disposed in the radiator circulation system to transfer energy between the TESM and a fluid passed over the third coil.